Beijing Duck Serum Contained Primarily In Lipoprotein Structure And Certain Functions

Epidemiological investigation suggested that the level of serum HDL was negatively related to the incidence of coronary heart disease. Beijing duck serum contains very high content of high density lipoprotein (HDL) which amounts about 75% of the total serum lipoproteins. Furthermore, experiments of Vang et al showed that Beijing duck would not develop atherosclerosis (As) on a high cholesterol and high fat diet. However, the mechanism of HDL anti-atherogeneity has not been completely elucidated yet. The purpose of this thesis is to study the structures and some of their functions of Beijing duck serum main apolipoproteins (apo) in order to look insight into the role of HDL on the prevention of atherosclerosis.Al first all main apolipoproteins of Beijing duck serum HDL and soluble apoVLDL were isolated by High Performance Liquid Chromatography (HPLC). It has been found that there were five main apolipoproteins in Beijing duck HDL. Their molecular weights, isoelectric points, isoforms, succharides, amino acid (a.a.) compositions etc. were then determined by SDS-PAGE, IEF electrophoresis, Schiff's reagent method and a.a. compositon analyzer. According to the results obtained we have assigned the apolipoproteins as duck apo A-I, apo C—III , apo CIII , apo C's and maybe apo A—III. Except apo C—III all other apos showed several isoforms on IEF, and apoCs is an apo's complex. Besides, four apolipoproteins from duck soluble apoVLDL were also isolated. They were disignated as apo Cs with a MW of about 10000 and the other one is a protein of MW. of about 65000 daltons. Furthermore the complete a.a. sequence of Beijing duck apo CIII and partial a.a. sequence of apo A-I were determined respectively by a.a. sequence analyser. The complete primary structure of Beijing duck apo CIII was reported in the world for the first time. On the basis of its primary structure, the seconary structure of duck apo CIII was also deduced by Chou and Fasman method. In comparison with human apoCIII, the homogeneity of apo CIII between the two species on their primary structure was very low, but high similarity was found on their secondary structures. These findings indicated that duck apoCIII should has functions similar to that of human apoCIII. In the meantime, we have also deduced the secondary structure of human apoCM which has distinctive function from that of human apoCIII. The deduced secondary structure of human apoCM can explain satisfactorily the relationship between the structure and fucnction of human apoCII. It proves the reliability of Chou and Fasman' method for predicting the secondary structure of the apos. On the basis of...